I photographed this MQM-15A Regulus II at the Frontiers of Flight in Dallas. This was the prototype for a supersonic cruise missile for US Navy, designated XSSM-N-9 and used in 1957-1958. After 1958 used as target drone, designated KD2U-1, in 1963 redesignated MQM-15A.
An example of the earlier USN Regulus Cruise Missile is on display at Pearl Harbor.